Third Generation Project Partnership (3GPP) Long Term Evolution (LTE) is often marketed as “4G” and represents the latest standard for wireless communications networks. LTE utilizes an Internet Protocol (IP) Multimedia Subsystem (IMS) framework, which leverages packet-based signaling. However, LTE also offers support for previous technologies (marketed as “2G” or “3G”), such as Universal Mobile Telecommunications (UMTS) platforms, Global System for Mobile Communications (GSM) platforms, and Code Division Multiple Access (CDMA) platforms, all of which utilize a different air interface than LTE and can operate according to circuit switching technology rather than packet-based technology.
For example, LTE allows a circuit switched fall back (CSFB) procedure, in which an LTE handset can leverage existing infrastructure of previous 2G or 3G technologies to make or receive a voice call. In other words, the LTE handset can drop an existing LTE connection with an LTE evolved Node B (eNB) and fall back to a 2G or 3G cell (e.g., Node B or base station). Upon completion of the call, the LTE handset can then re-establish a connection with the LTE network.
However, prior to dropping the LTE connection, a radio resource control (RRC) connection according to 3GPP LTE standard TS36.331 is first established in order to pass information to the handset relating to the target 2G or 3G cell that will manage the CSFB call. Once this RRC connection is established and the relevant information has been passed to the handset, the RRC connection is immediately terminated. Thus, when utilizing the CSFB approach, a significant amount of signaling is performed, which leads to increased resource utilization and call setup times. Hence, operations to reduce such signaling or to reduce the call setup time can be quite beneficial.
As noted, the current implementation of CSFB requires an initial RRC connection. As such, there are numerous existing enhancements and/or change requests (CR) that can reduce call setup time when the LTE handset already has an existing RRC connection (e.g., is in an RRC connected state). For example, TS25.331 CR4118, TS36.331 CR0402, and TS36.306 CR0029 have been accepted into the LTE standard to reduce call setup time, yet these enhancements only apply when the handset is already in an RRC connected state. Unfortunately, the LTE handset is not always in an RRC connected state. In fact, research shows that for a significant majority of the time, the LTE handset will be in an RRC idle state when a CSFB call is requested. Current approaches offer no adequate way to reduce CSFB setup time when associated user equipment is in an RRC idle state and/or not in an RRC connected state.
The above-described deficiencies are merely intended to provide an overview of some of the problems of conventional systems and techniques, and are not intended to be exhaustive. Other problems with conventional systems and techniques, and corresponding benefits of the various non-limiting embodiments described herein may become further apparent upon review of the following description.